Electronic device having a single-sided circuit board

Abstract

In one embodiment of the present invention, an electronic device comprises a circuit board having a first side and a second side and having circuit traces formed only on the first side. The electronic device further includes a voltage regulator providing a regulated voltage via a regulated voltage output terminal and having a regulated voltage return terminal. Additionally, the electronic device includes a microcontroller mounted to the first side of the circuit board and having a plurality of regulated voltage input terminals and corresponding microcontroller voltage return terminals. The electronic device also comprises a bus comprising a first circuit trace coupled to the regulated voltage output terminal and a second circuit trace coupled to the regulated voltage return terminal, the first circuit trace and the second circuit trace running substantially parallel to one another. Furthermore, the electronic device include a plurality of supply conductors, each coupled to the first circuit trace and to one of the regulated voltage input terminals; and a plurality of return conductors, each coupled to the second circuit trace and to one of the microcontroller voltage return terminals. Designs according to the present invention can provide excellent radiated emissions performance with an economical single-sided circuit board and a minimal number of T-filters.

What is claimed is:  
     
       1. An electronic device comprising: 
       a circuit board having a first side and a second side and having circuit traces formed only on said first side and having at least one stepper motor mounted to said circuit board;  
       a voltage regulator providing a regulated voltage via a regulated voltage output terminal and having a regulated voltage return terminal;  
       a microcontroller mounted to said first side and having a plurality of regulated voltage input terminals and corresponding microcontroller voltage return terminals and said microcontroller further includes an integrated stepper motor drive capability and is coupled to control said at least one stepper motor;  
       a bus comprising a first circuit trace coupled to said regulated voltage output terminal and a second circuit trace coupled to said regulated voltage return terminal, said first circuit trace and said second circuit trace running substantially parallel to one another; and  
       a plurality of supply conductors, each coupled to said first circuit trace and to one of said regulated voltage input terminals;  
       a plurality of return conductors, each coupled to said second circuit trace and to one of said microcontroller voltage return terminals.  
     
     
       2. An electronic device as recited in claim  1 , further comprising at least one gauge pointer, each gauge pointer coupled to be driven by a said stepper motor. 
     
     
       3. An electronic device as recited in claim  1 , wherein: 
       said supply conductors are wires routed on said second side of said circuit board and coupled to said first circuit trace through holes in said circuit board; and  
       said return conductors are wires routed on said second side of said circuit board and coupled to said second circuit trace through holes in said circuit board.  
     
     
       4. An electronic device as recited in claim  1 , wherein: 
       said microcontroller a said regulated voltage input terminal and a corresponding microcontroller voltage return terminal dedicated to a microprocessor core section of said microcontroller; and  
       said electronic device further comprises a filter coupled across said regulated voltage input terminal dedicated to said core section and that voltage input terminal's corresponding microcontroller voltage return terminal.  
     
     
       5. An electronic device as recited in claim  4 , wherein said filter is a T-filter. 
     
     
       6. An electronic device as recited in claim  5 , wherein said T-filter is the only T-filter coupled across any of said regulated voltage input terminals and corresponding microcontroller voltage return terminals. 
     
     
       7. An electronic device as recited in claim  1 , wherein said microcontroller voltage return terminal corresponding to said regulated voltage input terminal dedicated to said core section is returned to said second circuit trace closer to said voltage regulator than the remaining said microprocessor voltage return terminals. 
     
     
       8. An electronic device as recited in claim  7 , wherein said microcontroller voltage return terminal corresponding to said regulated voltage input terminal dedicated to said core section is electrically coupled to a ground plane formed on said first side of said circuit board. 
     
     
       9. An electronic device as recited in claim  8 , wherein said ground plane is located substantially beneath said microcontroller. 
     
     
       10. An electronic device as recited in claim  9 , wherein: 
       said electronic device further comprises an oscillator coupled to said microcontroller; and  
       said oscillator includes a ground terminal coupled to said second circuit trace via a common return conductor as a microprocessor voltage return terminal corresponding to a regulated voltage input terminal dedicated to said core section.  
     
     
       11. An electronic device as recited in claim  10 , wherein said oscillator is a crystal oscillator. 
     
     
       12. An electronic device as recited in claim  1 , wherein said first circuit trace and said second circuit trace are adjacent to one another, with no circuit traces disposed therebetween. 
     
     
       13. An electronic device as recited in claim  12 , wherein said first trace and said second trace are spaced less than two millimeters apart. 
     
     
       14. An electronic device as recited in claim  13 , wherein said first trace and said second trace are spaced approximately one millimeter apart.